1. Field of the Invention
The present invention relates to a driving apparatus of a curtain using a linear motor and particularly suitable to be installed in a place containing a curved portion.
2. Description of the Relevant Art
Generally, a linear motor has been known as a linearly driving motor and is practically applied to a robot, an X-Y printer and a driving apparatus of a curtain in a small scale field and a railway and the like in a large scale field.
A window of a station wagon as shown in FIG. 6 is fitted with a curtain, while the curtain of this type is usually small and furthermore the installed portion of the curtain is often curved.
Heretofore, a driving apparatus of such a curtain fitted to the window of the automobile is disclosed in, for example, Japanese Utility Model Application Laid-open No. 98489/1985, entitled "An Automatic Opening and Closing Apparatus of a Curtain". The apparatus of the application utilizes a linear motor comprising a housing which forms a curtain rail shaped into a reversed U-letter in section, a magnetic pole portion in the form of a guide rail disposed within the housing in opposite relationship with the housing in the longitudinal direction of the housing to generate uniform magnetic flux in a gap between the housing and the portion, and a movable coil which can be guided by the magnetic pole portion in the form of a guide rail to be moved in the gap perpendicularly to the magnetic flux.
The above conventional apparatus utilizes the force produced when a current flows through the movable coil disposed in the magnetic flux and has an advantage that the movable coil can be thinned relatively, although the apparatus has the following defects.
Firstly, the electromagnetic force acts on only a vertical portion of the movable coil and does not act up any other portions of the coil. Accordingly, most portion of the coil are not useful and in order to obtain the desired electromagnetic force for driving the movable coil must be made correspondingly larger. Consequently, the whole structure of the apparatus is made larger and is not suitable for the curtain of the automobile which requires a small driving apparatus therefor as described above.
Secondly, while there are many curved portions in the installed place of the curtain in the automobile, the movable coil can not follow the curtain rail along the curved portion since the length of the movable coil in the longitudinal direction thereof is long due to the large size of the coil. Accordingly, since the curtain rail must be divided to be disposed in only a straight portion or limited to be disposed in a relatively large curved portion, the design in the installation of the curtain rail and the design of the curtain are extremely limited.